ALLEN PARK -- Nick Fairley has fought a long, often losing battle with his own weight.

He's subsequently underachieved during his three seasons with the Detroit Lions, and that has caused many outside the organization to believe he is a locker-room cancer.

But that is antithetical to the real Nick Fairley.

The defensive tackle is outgoing. His humor and energy are infectious. He's charismatic.

Teammates absolutely love him.

And that's why it pains them to see Fairley still struggling to bull-rush his own demons.

"I don't know where his head's at. I wish I knew," C.J. Mosley said. "If I knew, man, I'd grab his head and bring it back to where it's supposed to be. I just don't know.

"I try talking to him, and I try encouraging him. That's something I've always done. I love Nick, man, and just want to see him reach his potential. That dude doesn't know how good he could be. And it hurts to see him like this."

Mosley is the guy who took Fairley's spot in the starting rotation. He's also a 10th-year veteran who knows a thing or two about trying to battle through off-field problems.

On the first day of his rookie training camp with the Minnesota Vikings in 2005, Mosley woke up to a phone call with the following news: His mother, Angela, had breast cancer. His grandfather who helped raise him, Richard Hope, had a stroke. And his grandmother, Sarah Hope, already was in the hospital because of a stroke.

Both grandparents died during that camp, and his mother followed two years later.

Mosley played on, though. And a decade later he's still in the league, vying for a starting spot on a team that starts a pair of first-rounders at his position.

Now Mosley is trying to counsel Fairley through his struggles to meet the expectations of his new coaching staff.

"This is my 10th year, so I've seen guys kind of venture off before," Mosley said. "He's just got to be strong for himself. Decide on his own what he wants to do. I care, man, and I want to see him figure this stuff out."

What does he mean by "venture off?"

"For myself personally, I've had a lot of things outside of football that might have been distractions that caused you to have your mind somewhere else," Mosley said.

"I don't know if that's what he's going through -- we haven't had that talk -- but it looks like something's on his mind. Whatever it is, we're here for him, I'm here for him, we want him to do his best. Just like everybody else."

Fairley's best is pretty good. General manager Martin Mayhew said earlier this offseason he believes Fairley is as talented as All-Pro Ndamukong Suh.

And Suh, not known to give out empty compliments, agreed with that sentiment this week.

"I haven't said this a lot, or to many people, more or less, but Nick is more athletically gifted than me," Suh said. "He has an opportunity to be better than me. And that's what I want to see out of him."

The problem, though, is Fairley is too infrequently at his best. And now he's struggling to keep up with Mosley, let alone Suh.

That's a function of possible off-field distractions, as well as his weight, which climbed north of 320 pounds during camp.

Fairley remains mired in a funk on the field, too, where he recorded just one tackle against Oakland and failed to generate much push.

His body language has been poor during practice. He's isolated himself from teammates, and provided poor effort on several drills that were available to the media.

That has caused Fairley to remain on the second team for a second consecutive week. He likely won't be in the lineup Friday night against the Jacksonville Jaguars.

"Our job is to try to get our guys to play well, no matter what it takes," defensive coordinator Teryl Austin said. "Not everybody's going to be a guy that's a self-starter, work over the top all the time. There's different ways that you have to motivate guys and get them going, and that's part of our job to figure out, 'Hey, what makes a guy tick? What's going to help him play well?'

"We're doing whatever we can to try to do that because we feel the guy's super talented, he's a good guy, and we just want him to -- we'd love him to play great, and I think he's on track now."

Fairley continues to draw criticism for his weight, his fitness and his performance. But he still has the support of the Lions, and teammates are hoping he sorts himself out.

"I'm always going to encourage Nick," Suh said. "I always want him to be the best player he can be."